Whats new in v.4.1.1:
-converted menyoo map into ymaps as add-on
-its stable no crash
-whole North Yankton surrounded by mountains
-all island is stable with collision even mountains
-cars and planes placed by ymaps
-working train Los Santos->North Yankton->Los Santos
-many new buildings
-version 4.1.2 will be released for public as BETA

This mod will be upgraded (still learning new things :D)
And heres preview:

v.4.1.3 WIP - in this version things to do:
-no teleports - only working interiors with doors
-more safehouses and misc buildings
-fixed green bridge
-add new bridge for train and train tracks with train stations and working train
-more trees
-new airport
-new small city
-ski resort with mountain
-new cars

Heres another progress:
(things ive made)
-reworked full map - removed embedded collisions and placed static with proper effects of snow, added LODs for buildings and other objects, reworked existing buildings in Ludendorff to enterable with interiors, remaded old interiors now you can enter every interior by working doors - no more teleports, named 2 cities Lesterville and Vermillion, added more enterable (new) buildings, mod is 100% compatible with Travel to NY mod, added snowmobile and custom emergency cars for each city (police firetrucks and ambulance)
(things left to do)
Train stations on ground and underground with working path, add new trafic paths, more interiors and buildings, new city Jefferson, more trees and details, more parked cars/planes, reworked road conecting SA and NY and few other thing. Progress will be posted here like usual and heres some videos: